This invention relates to photographic couplers that comprise a silyl substituent in a non-coupling position, and to photographic materials and processes using such compounds.
Images are commonly obtained in the photographic art by a coupling reaction between the development product of a silver halide color developing agent, particularly an oxidized aromatic primary amino developing agent, and a color forming compound commonly described as a coupler. The dyes formed vary depending upon the composition of the coupler and the developing agent. The subtractive process of color formation is typically employed in multicolor photographic elements. Resulting dyes are typically cyan, magenta and yellow dyes formed in or adjacent to silver halide layers sensitive to radiation complementary to the radiation absorbed by the image dyes, that is, silver halide emulsions sensitive to red, green and blue radiation.
Couplers that contain various substituents in the non-coupling positions of the couplers are known. Examples of such couplers are described, for example, in U.S. Pat. No. 3,772,002, and in Research Disclosure, December 1978, Item 17643, Section VII. These substituents serve different functions, acting, for example, as ballast groups or groups that affect the solubility or dispersibility of the coupler, or the hue of the dye formed from the coupler.
There has been a need for a new class of couplers comprising substituent groups in non-coupling positions of the couplers that enable modification of the hue of the dye formed upon oxidative coupling of the coupler without significantly adversely affecting other desired properties of the coupler, such as image stability, dispersibility, and low melting point.